This PDF file contains the front matter associated with SPIE Proceedings Volume 11326, including the Title Page, Copyright Information, Table of Contents, Author and Conference Committee lists.

The increase in the demand of sub-10 nm feature size in semiconductor industries necessitates a new kind of resist material development which can absorb a large fraction of irradiation and retains the small size cluster distribution (1-2 nm). In this context, we developed a novel nickel-based organo-metallic cluster comprising high optical density inorganic nickel as metal building units (MBU), and 3,3-Dimethylacrylic acid as an organic ligand to form Ni-DMA clusters. The synthesised clusters have ~1 nm size with narrow size distribution. The formulated resist shows the negative tone pattern when exposed with a focused helium ion (He⁺) beam and e-beam. The high-resolution line patterns of ~8 nm at the dose of ~40 μC cm^-2 were obtained with the minimum line edge roughness (LER) and line width roughness (LWR) of 2.16 ± 0.04 nm and 3.03 ± 0.06 nm, respectively.

Antimony(V) carboxylate photoresists incorporating polymerizable olefins have demonstrated high photospeeds. The work of Passarelli et al. reported a sensitivity hypothesis, polymerizable olefin loading (POL), in which an increase in photospeed correlates to an increase in the number of olefins per molecular weight of resist.1 Utilizing this sensitivity trend, a photoresist of higher molecular weight, triphenylantimony(V) bis(4-vinylbenzoate) (JP-30), was developed exhibiting moderate photospeed at the cost of improved pattern fidelity. Herein we report three approaches for improving the lithographic performance of polymerizable olefin antimony carboxylate photoresists. Approach 1 increased the number of olefins per molecule through functionalization of the R-group. Tristyreneantimony(V) dicarboxylate photoresists were lithographically evaluated exhibiting high photospeeds and improved resolution capabilities (Figure 1). Approach 2 examined the benefits of blending two antimony carboxylate photoresists with high and low POL values and observing the changes in photospeed. Approach 3 increased the POL relative to JP-30 through reduction in molecular weight of the R-groups by the synthesis and lithographic evaluation of trimethylantimony(V) bis(4-vinylbenzoate).

The inherent local inhomogeneity in a uniformly average distribution of dissolution aiding events is shown through an algebraic model to be the likely source of missing contacts in projection printing in positive photoresist resist. A granular model of dissolution with voxels 1-3% of a contact core volume having Poisson statistics is used to show that a configuration of 5-10 voxels with stochastically low dissolution aiding events can block a resist etch front or polymer disentanglement at nominal exposure conditions. To drive missing contact error rates to 10^-13 for 25 nm contacts requires increasing the normal event density by 59% which is 8-9% per decade error rate reduction. In scaling, the event density increases as the inverse of the cube of contact size. For 12 nm contacts an alternating phaseshifting mask may be enabling.

In this work, we connected the analytical determination of the EUV Dill C parameter for different photodecomposable base quencher (PDB) architectures using a standard addition method, the influence of the underlying hardmask on postdevelop EUV resist residue formation, and the vertical PAG and PDB concentration profile throughout the depth of the film determined by GCIB-TOF-SIMS for a model EUV resist system. The collected experimental data was used to feed a resist patterning simulation engine, in order to understand the additive effect of component distribution and efficiency on EUV stochastics and its potential impact on defect control. Our results unveiled a link between PDB quantum yield and nanoscopic material distribution uniformity. In parallel, a differentiating behavior was observed among inorganic underlayers: metal oxide hardmasks (HMs) invariably induced more resist residue than non-metallic HMs. Last, a specific example of joint PAG and PDB concentration depletion at the resist-substrate interface was related to a potential increase in microbridge defectivity as a result of poor stochastic counts.

Flood Exposure Assisted Chemical Gradient Enhancement Technology (FACET) is introduced for improvement in EUV resist resolution, process control, roughness, patterning failure and sensitivity. Experimental EUV exposure latitude was enhanced (~1.5 times) with FACET using the assist of UV flood exposure. The mechanism of the process window improvement by FACET is explained by non-linear resist coloring (enhancement of UV absorption) vs. EUV exposure dose to enhance acid image contrast during UV flood exposure. To balance chemical gradient enhancement and stochastic effects, Stochastic Aware Resist Formulation and Process optimizer (SARF-Pro) with a fast stochastic simulation model is created. SARF-Pro predicts stochastic patterning failure risks, and optimizes resist formulation and processes by putting emphasis on stochastic variation across patterns. Photosensitized Chemically Amplified ResistTM (PSCARTM) 2.0 with FACET and standard chemically amplified resist (CAR) optimized in SARF-Pro suggests that PSCAR 2.0 with FACET has the potential of better process window, roughness, sensitivity and, we hypothesize, reduced risk of stochastic defects compared with standard CAR.

In this presentation, we will show our efforts for the discovery of high-performance imaging reactions based on fluorine and radical chemistry working under high-energy radiation. Prior to this study, we have reported molecular resists equipped with rather flexible perfluorinated alkyl ether (PFAE) chains and their imaging behavior as negative-tone resists under electron beam irradiation. In this study, we turned our attention to another fluorinated unit, fluorinated aromatic compounds, possessing structural rigidity that we believe contributes to achieving improved patterning capabilities. Successful coupling reactions between a phenolic resist core and fluorinated arenes provided fluorinated molecular resists, which we evaluated in terms of imaging behavior under e-beam and EUV lithographic conditions. The solubility of their thin films was decreased by the high-energy radiation; thus, negative-tone patterns down to 30 nm half-pitch could be obtained after development in fluorous solvents.

A new non-CAR hemicellulose resist is proposed for use in high-NA EUV lithography. This resist has high sensitivity (EUV dose 34.4 mJ/cm²) and high resolution (half-pitch of more than 16 nm) compared to conventional chain scission resists. Additionally, the process flow is very simple (no need for PEB) and the resist film is stable throughout the process. It was confirmed that the RIE selectivity ratio (Si/resist) of the non-CAR hemicellulose resist was 3.7, and am L/S pattern was obtained with a Si depth of 120.4 nm and a half-pitch of 18 nm. Furthermore, a new resist process, PreMi (pre-exposure metal insertion), was proposed. The PreMi process is expected to improve the fabrication properties, increase sensitivity and contrast, and reduce defects. Te and Sn were employed as metal types in this study, and EUV L/S patterns of PreMi-Te and PreMi-Sn were obtained. It was confirmed the PreMi process improved the fabrication properties of the no-PreMi process by a factor of 2. The non-CAR hemicellulose resist and PreMi process have great potential for use in high-NA EUV lithography.

Introduction of EUV lithography using soft X-ray at wavelength of 13.5 nm has been started because of demand for miniaturization at low cost in mass production of semiconductor devices. Chemically amplified resist (CAR) has been utilized for many years and is also one of the promising materials for EUV resist. However, resist performances (resolution, line edge roughness, and sensitivity) show trade-off relationship and the searching for the solution has been still a serious problem. In the previous work, our group has shown that addition of Di-p-tolyl sulfone (DTS) into CAR increases acid generation efficiency (acid-generating promoter (AGP)). DTS acts as deprotonation promoter and recombination inhibitor between ionized polymer and electron. The resist performance upon exposure to electron beams (EB) was improved. In this study, we investigate the sensitivity of CAR to 13.5 nm EUV light upon adding new diphenyl sulfone derivatives. EB lithographic effects by adding some diphenyl sulfone derivatives were also studied. And the detail roles of AGP are also discussed.

Although EUV process was actually inserted to HVM as realistic photographic scaling driver relieving from Multiple patterning, process/material induced defect, especially missing type defect on via hole, must be serious problem and it is really considerable subject. In our previous work, the existing of latent defect around hole bottom was examined and effective solution for defect suppression utilizing robust etching technique was introduced [1]. Additional de-scumming process before etching of under SoG layer has wider capability to suppress the missing hole defect, however, photolithographic relevant problem has to be solved in photolithography area. In this study, assuming that the origin of not-opened hole might be insolubilized potion in photo-resist film, we examined mainly interfacial reaction between photo-resist and under-layer. Historically, adhesive work(W) have been studied to prevent the peeling or collapsing of resist pattern mainly [2][3][4]. In order to understand the reason to be insoluble the solubilized region despite exposed, de-protected and polarity changed. This paper would introduce our examination results about the infliction of resist adhesive work with modified underlayer surface and mention about our explorations of insolubilized mechanism.

The photo-mask in lithographic process of semiconductor device has an important role to transfer the downsized target image to the wafer. Due to the development of information society, demand for semiconductor devices has been growing. In order to increase photo-mask manufacturing throughput, the current density of electron beam (EB) has been getting higher. EB exposure increases the resist temperature on mask substrate inhomogeneous depending on its current density, shot size, writing order and etc. It is known that the resist sensitivity increases with irradiated resist temperature (heating effect). So, inhomogeneous temperature increase of resist on mask substrate disturbs precise pattern formation. However, the physical or chemical mechanism of heating effect has been still unknown. Here, we examined temperature dependence of acid generation process in chemically amplified resists (CARs). Poly(4- hydroxystyrene) (PHS) and poly(4-[(tert-butoxycarbonyl)oxy]styrene-co-4-hydroxystyrene) (PTBSHS) were used as CAR resin. Monte Carlo simulation moving thermalized electron under the electric field between polymer radical cations were performed with changing the temperature. From the simulation, it was revealed that the energy increase of thermalized electron contributes to the acid yield by 0.038 %/K. Quantification of the acid yields in resist films upon exposed to EB were performed with changing the temperature by titration method using Coumarin 6 (C6) as an acid sensitive dye. The acid yield increased by 0.14 %/K in PHS film and 0.21 %/K in PTBSHS film, respectively. Both values were higher than the simulation value (0.038 %/K). Pulse radiolysis experiment was also performed to observe deprotonation of polymer radical cations at 298 and 343 K. The decay of dimer radical cation of PTBSHS became 1.6 times faster at 343 K than that at 298 K. From the results, it is suggested that the heating effect mainly caused by the temperature dependence of deprotonation rate from the radical cations of PTBSHS.

Linewidth Roughness (LWR) remains a difficult challenge in resist materials. In previous work we focused on showing how roughness Power Spectral Density (PSD) parameters were affected by aerial image and basic resist parameters such as diffusion. This highlighted the relationship between PSD(0) and correlation length in optimizing LWR. By measuring the unbiased PSDs with MetroLER we showed LWR measurements could be expressed as a ratio between the roughness PSD parameters. In this paper we show how LWR improvement can be achieved by several strategies that focus on both PSD(0) and correlation length and not a single LWR number.

Recent advances in machine learning and deep learning have provided an opportunity for improvement in the field of lithography. Compared with the numerical simulation, machine learning/deep learning may provide much faster and more efficient performance, but they provide less accurate solution due to the limitation of the statistical approach. Typical machine learning models cannot take into account complex multiple processes such as UV exposure, photoreaction and photo-resist development in lithography. In this work, we developed a newly designed deep learning algorithm not only to improve the model accuracy but also to overcome data limitation. By combining a physics-driven machine learning model and a complex-valued neural network (CVNN), we designed a novel machine learning model structure. Applying CVNN to phase shift mask analysis could improve the model performance dramatically. As such, this work opens up a new class of photo-lithography analysis by using a novel neural network model.

We demonstrate a simple ex-situ inorganic infiltration route for transforming standard organic resists into high-performance positive tone hybrid resist platform. A model thin film PMMA-AlOx hybrid resist system has been synthesized by hybridization of PMMA with AlOx and investigated for electron beam lithography. The approach possesses full controllability of the resist performance in terms of critical does, patterning contrast reaching up to 30 and etch resistance for plasma-based pattern transfer processes. The high selectivity Si etching capability demonstrated using a low-temperature cryo-Si etch process, based on the controlled infiltration outperforms commercial resists and typical hard mask material thermal SiO₂, with estimated achievable selectivity in excess of ~300. Si nanostructures down to ~30 nm with aspect ratio up to ~17 are also transferred into the Si substrate. Easy implementation and adaptability for different inorganic infiltrations, this platform is well capable of potentially delivering the resist performance and throughput necessary for EUV lithography.

The availability of EUV lithography is the mainstream for resolving critical dimension of the advanced technology nodes, currently in the range of 18nm and below [1]. The first insertion of EUVL into manufacturing utilizes chemically amplified resist (CAR) [2]. The filtration of CAR, both at bulk and point-of-use (POU), has already demonstrated in ArF and ArF immersion lithography to play a significant role for microbridges reduction essentially by removing hard particle and gels [3-6]. With respect to ArFi, EUV is bringing new challenges not only for the achievement of the required line roughness, sensitivity and resolution, but also for the need of a substantial reduction of defects such as line collapse, microbridges and broken lines. In this study, it demonstrated the ability of utilizing novel POU filtration to modulate microbridges and achieving superior start-up behavior, both crucial for enabling EUVL at high volume manufacturing. Different POU filters were tested at the imec EUV cluster comprised of TEL CleanTrack LITHIUS Pro-Z and ASML NXE:3400B. The start-up performance, assessed by measuring defects down to 19nm size as a function of the flushing solvent volume, has shown the fast achievement of attaining a stable baseline. Lithography experiments targeting reduction of on-wafer defectivity, carried out with commercially available photoresists, have consistently shown a substantial reduction of after resist development (ADI) and after resist etch (AEI) microbridges on a 16nm L/S test vehicles. The effect of membrane physical intrinsic designs and novel cleaning of POU devices are discussed.

3D NAND has become the mainstream technology to support bit growth of NAND Flash. The main challenge of 3D NAND is the increased level of wafer deformation as more layers are stacked vertically. This global deformation of the substrate leads to a significant degradation of overlay performance. One potential way to address this challenge is through bow compensation by wafer backside deposition. However, it turns out that standard backside processes sometimes do not improve overlay. This study investigates this phenomenon and explores how to counter high levels of wafer deformation in a way that overlay performance does not deteriorate. Scanner monitor wafers with etched reference marks have been modified to create a variety of global warp levels, covering a wafer bow range from +300μm (bowl shape) to -550μm (umbrella shape). Subsequently, several different backside deposition processes have been applied to these wafers. Flat reference wafers, warped wafers, and compensated wafers have been then measured on NXT scanners with different wafer tables. Non-linear overlay residuals of these wafers from about 1nm (flat reference wafers) to more than 30nm (uncompensated highly deformed wafers) have been measured. The obtained data reveal clear correlations between overlay, global wafer shape and backside deposition. A demonstration of the optimized overlay performance on wafers with large warpage values will be shown with a detailed analysis through absolute overlay metrology.

Further increasing integrated circuit storage capacities while reducing the cost has led to the development of stacked 3D structures for NAND application. The 3D NAND structures can be enabled by using KrF photoresist coated at high thickness, and a staircase pattern can be generated through multiple etch steps. Pushing KrF lithography to high coating thickness creates several challenges for the materials and formulation design, such as lack of film transparency, as well as film cracking and delamination. The photoresist used in KrF lithography is based on poly(hydroxystyrene) (PHS) type polymers, which is associated with unique technical challenges for printing 10s microns scale features due to its high absorbance at 248 nm and its high glass transition temperature, Tg. Here we report the development of novel KrF photoresist materials for 3D NAND application with sufficient film transmittance, which forms desired straight profile with no footing. Our results also indicate that the film cracking could be mitigated by additive and process condition optimization, and film delamination could be addressed by adding an adhesion promotion layer.

CMOS optical sensors performances are mainly driven by the quantum efficiency and the pixel cross talk. Microlens arrays implementation is a way to improve both by focalizing the incident light on the active photodiode area. Further optimizations include fill factor maximization by reducing the space between microlenses.

In this study we propose the fabrication of zero gap microlens arrays by plasma etch transfer of reflowed microlenses into a subjacent resist layer. The impact of lithography, reflow and etch process parameters on microlenses shape and space reduction are discussed. We show that etch time increase allows gap reduction down to zero, while polymerization control is key to conserve microlens height.

The impact of 3 process factors on the final microlens shape are studied using DOE (design of experiment) methodology. Thus, microlenses gap and height evolution as a function of mask thickness, polymerizing gas flow and etch time are modeled within the experimental range of these factors. An optimum process point is then proposed to minimize the gap while keeping constant the microlens height.

In this work, a novel chemical-free technique is proposed to remove adsorbed particles of less than 100 nm from a substrate. More specifically, the small particles buried under the "stagnant layer" were removed using a process that relied on the force generated by volumetric expansion on rapid freezing of supercooled water. In the process, water penetrated into the small (narrow) spaces via the capillary force; it then flowed into the narrow interfacial gap between the substrate and particles, and lifted the particles off the substrate via the volumetric expansion force on ice formation. Because fine patterns have no such gaps, they are not damaged during this process. In other words, unlike conventional cleaning technologies, such as mega sonic cleaning and two-fluid jet cleaning, this cleaning process is able to specifically target the small particles while the fine patterns are unaffected.

Deposition-based patterning is becoming an important need in advanced manufacturing. Several new approaches are emerging where chemical etching is being coupled with atomic layer deposition to achieve area-selective deposition of dielectrics and metals. During ALD, selectivity is generally lost when undesired nuclei form on the targeted non-growth surface. These undesired nuclei can sometimes be removed by periodic etching, improving the overall selectivity. However, it is not known to what extent these coupled deposition/etching sequences can proceed while maintaining good selectivity. As desirable deposition and etching reactions proceed, other changes in the process can occur to enhance unwanted nucleation and/or impede desired etching, thereby limiting the net selectivity. Recent experiments in our lab have used in-situ probes to explore coupled thermal ALD and ALE super-cycles, performed sequentially under isothermal conditions in a single reaction chamber, to achieve area selective deposition of TiO2 on SiO2 with hydrogen-terminated silicon (100) as the desired non-growth surface. We find that as ALD/ALE super-cycles proceed, small changes occur in the ALD and ALE reactions, particularly during the transition from ALD to ALE, or from ALE to ALD. Likewise, a new thermally-driven ALE process for tungsten has been applied in ALD/ALE super-cycles to improve W ASD. In this case, the ALE process alters the ALD surface leading to significant changes in the ALD. Modeling studies allow us to quantitatively analyze the ASD results and compare our findings to other known approaches. These insights will be helpful to understand opportunities and challenges in advanced deposition-based patterning.

Area selective deposition (ASD) strategies are broadly enabling, where their application is anticipated to impact semiconductor scaling, in the short term, and broadly impact the design of non-traditional hardware such as phase change memory for specialized artificial intelligence (AI) hardware. In order to extend scaling, ASD may be required for the formation of self-aligned structures on patterned substrates that enable schemes, such as fully aligned via. The design of inhibiting materials including small molecule, polymer brushes and area selective surface polymerizations can be tailored to enable the selective deposition of a variety of metal oxide films (e.g., Al2O3, TiO2 or ZnO). The inhibiting materials examined systematically varied inhibitor spacing, composition and surface cleans prior to inhibitor deposition. The examination of a range of materials provides insight into the fundamental mechanisms of inhibition between precursor chemistries and their interaction with surfaces. Furthermore, while the materials generally exploited for inhibition are relegated to small molecules and may require multiple cycles of etch-back processes followed by renewal of the surface inhibitor polymeric materials may offer the potential to access ASD of films with devices that have significant surface topography where they act as effective inhibitors over small molecules. This was achieved with the area selective growth of polymers where the area selective control of a polymerization on a 100nm tall copper line space feature enabled the selective deposition on a silicon dielectric. In addition, while the ASD of some film compositions could not be achieved with polymer inhibitors the ALD on polymer regions of a patterned film increased the porosity of the metal oxide changing the film’s etch resistance, this could be exploited to achieve the area selective etch of metal features.

Continued reliance on 193nm immersion lithography with multiple patterning is becoming much more difficult as line widths decrease. With the use of Self-Aligned Quadruple patterning and related patterning schemes, it is critical to minimize variability, where high quality films must be deposited and etch rates must be very precise. To this end, a better understanding of spacer material properties must be obtained. Initial work has been performed to examine the resulting film properties for TiO₂ and Al₂O₃ spacer materials deposited by low temperature ALD with the use of various oxidants (H₂O₂, H₂O, O₃). Improved film quality has been demonstrated for films deposited with H₂O/H₂O₂ mixtures used as the oxidant. Key to advanced patterning applications is that improved etch resistance is achieved for both Metal Oxide materials. Also significant with regard to multiple patterning is that higher growth rates are obtained at reduced temperatures, enabling lower process temperatures for underlying sensitive materials. The all thermal nature of these deposition methods points toward improved film conformality on 3-Dimensional structures. Improved etch rates and improved electrical properties reflect overall improvements in Metal Oxide dielectric film quality with the use of Hydrogen Peroxide.

Self-assembled molecules (SAM) are used as an inhibitor in conjunction with atomic layer deposition (ALD) for selective area deposition. Given the extremely thin film and the pattern density involved in this type of process, currently available analytical tools have difficulty in analyzing the quality and selectivity of each processing step. For example, while FTIR may provide evidence of SAM coverage, it cannot assure the quality of coverage, especially on a scale relevant to current processing requirements. Similarly, electron microscopes that can provide excellent spatial resolution and elemental analysis cannot determine the quality of the ultrathin thin organic and selective inorganic deposition layers. In this paper, a relatively new technique called photo-induced force microscopy (PiFM), which combines atomic force microscopy (AFM) and infrared (IR) spectroscopy with sub-10nm spatial resolution, is used to analyze the deposition of SAM layer and subsequent alumina deposition on metal/SiO2 test patterns (80nm being the smallest pitch). PiFM spectra can unambiguously identify the different chemical species (SAM, SiO2, and alumina) via their IR signatures. PiFM images at fixed wavenumbers associated with the different chemical species provide chemical mapping in real space with sub-10nm spatial resolution, clearly illuminating how selective different processing steps are. The paper will show how the nanoscale hyperspectral PiFM data can provide unambiguous and speedy feedback to process engineers engaged in selective deposition.

Emerging memory devices, such as MRAM, RRAM, and PCM, plays an important role in in-memory computation technology which can lead to significant acceleration for machine learning and AI applications.[1-3] The basic structure of these memory cell is simply a pillar made of a wide range of materials, however, the local CD uniformity (LCDU) of the pillars is especially crucial for these memory devices. The stringent LCDU requirement derives from either the intrinsic small resistance difference between the two memory states or the requirement for creating a large number of memory states within a small range of resistance. Apparently, the stochastic variation in physical dimension will correspond to the variation in resistance from cell to cell, which will affect the correct readout of the memory states and fail the device. Because the “local” CDU in this context refers to the variation within the memory array, i.e. typically within several um, it is almost impossible to correct by utilizing existing advanced tools or process control techniques. In this work, we will demonstrate four promising options to address the stochastic effect in LCDU of pillars: a) adopting new resists, b) PTD and NTD shrink, c) DSA, d) cross-SADP. Fig. 1 shows the general approach to achieve better LCDU by printing larger CD at litho and shrink by post-litho processing.[4] Here we carefully characterize two shrinking techniques and its efficacy on LCDU improvement. Fig. 2 shows two alternative approaches, i.e. DSA and cross-SADP.[5] We will carefully explore these four approaches for LCDU improvement with thorough characterization and analysis. Subsequent pattern transfer and the retention of the LCDU improvement and cost/quality trade-off will also be discussed. Defectivity learning will also be discussed.

For the introduction of directed self-assembly (DSA) process into high volume manufacturing, the roughness of pattern is one of main check points. The focus of this study is to understand the origin of DSA roughness and to discuss the strategies to improve DSA-specific roughness. 3X DSA LiNe flow with PS-b-PMMA was used as a model case. Unbiased line edge roughness (LER) and linewidth roughness (LWR) were measured using power spectral density (PSD) analysis on CDSEM images. We found that low frequency LER is particularly sensitive to the assembly conditions. By optimizing material and process conditions, unbiased LWR was reduced by about 10%, while unbiased LER was reduced by about 15%.

Directed self-assembly (DSA) is one of the candidates for next generation lithography. Over the past years, many papers and presentation have been reported regarding DSA, and Tokyo Electron Limited (TEL is a registered trademark or a trademark of Tokyo Electron Limited in Japan and /or other countries.) also has presented the evaluation results and the advantages of each^1-9. Especially, the chemo-epitaxy process has advantages for the sub 20nm line & space patterns to apply to active area patterns for DRAM, fin patterns for Logic and narrow pitch of metal patterns. One of the biggest advantages of DSA lines is that the pattern pitch is decided by the specific factors of the block copolymer, and it achieves the small pitch walking as a consequence. In this paper, the latest results regarding the defect reduction work regarding chemo-epitaxy line & space pattern is reported. And, sub-10nm process flow without using high-chi BCP is discussed.

Directed Self-Assembly (DSA) of Block Copolymers (BCP) by chemo-epitaxial alignment is a promising high resolution lithography technique compatible with CMOS high-volume manufacturing. It allows overcoming limitations in resolution and local stochasticity by conventional, imaging based, lithography. However, for BCP with pitches below 20 nm and guide patterning by immersion lithography (193i), multiplication factors ≥ 4 become necessary, imposing stringent requirements on the guides and defectivity becomes hard to control. The Arkema-CEA (ACE) process flow overcomes this limit by creating the guides by a self-aligned double patterning (SADP) process flow, followed by the deposition of a cross-linkable neutral mat and selective grafting of the guides. This paper reports on the transfer of the process flow to immersion lithography, details challenges encountered in process optimization, notably the dependence of the wetting of the neutral layer on the surface energy and the morphology of the spacers. Last, the paper presents a metrology and defectivity roadmap combined with preliminary, promising results.

In response to the growing demand for Inpria MOx EUV resists, we have brought online our high-volume manufacturing (HVM) production line, have built the necessary supporting qualified supply chain and have developed the associated quality systems. In this paper we will discuss challenges we overcame in scaling and will review data demonstrating new achievements in reproducibility and stability of MOx photoresists. We will also present recent advances in integrated patterning capabilities for specific use cases of Inpria resists in logic and memory applications on the NXE:3400 as well as an update of resist performance on the EUREKA MET5.

The development of an EUV photoresist to support high volume manufacturing remains a challenging issue. Meeting the combined resolution, sensitivity, and line width roughness (RLS) requirements has proved difficult. Furthermore, defectivity issues arising from stochastic effects are becoming increasingly critical as pitches decrease. Whilst traditional chemically amplified resists will likely be used initially, a wide range of materials options are being examined for future nodes, aiming to identify a photoresist that simultaneously meets RLS and defectivity requirements. Irresistible Materials (IM) is developing novel resist systems based on the multi-trigger concept. In a multi-trigger resist, multiple elements of the resist must be simultaneously activated to enable the catalytic reactions to proceed. In high dose areas the resist therefore behaves like a traditional CAR, whilst in low dose areas, such as line edges, the reaction is second order increasing the chemical gradient. Effectively there is a dose dependent quenching-like behaviour built in to the resist, enhancing chemical contrast and thus resolution and reducing roughness, whilst eliminating the materials stochastics impact of a separate quencher. The multi-trigger material consists of a base molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). Research has been undertaken to improve this resist, in particular focusing on improving resist opacity and crosslinking density. A non-metal atom has been incorporated into the crosslinker and the results presented here show three iterations of this high opacity crosslinker. To improve the sensitivity, a mark II high-Z crosslinker was synthesised which incorporated longer arms compared to the mark I version, to reduce steric hindrance by increasing the distance of the high opacity atom from the reaction site. The results show a dramatic 65% dose-to-size reduction when using the mark II crosslinker. Further exposures investigated the effect of PEB temperature on both the mark I and mark II crosslinkers. This showed that the dose can be reduced by over 50% when using a 90 °C PEB compared to when using no PEB for the mark I crosslinker but by only 20% for the mark II crosslinker, as would be expected if steric hinderance has been reduced. We present results with the mark II crosslinker showing 16 nm half pitch lines using a 28 nm film thickness with a 90 °C PEB which results in a dose to size of 19 mJ/cm² and an LWR of 5.2 nm. A Mark III version is also presented where the chemistry of the Mark I crosslinker has been modified to improve the solubility in industry preferred solvents. We also present work aimed at improving the LWR of the high opacity resist formulation at high resolution, particularly aimed below 16 nm hp using dense lines when patterned using EUV lithography at the Paul Scherrer Institute, Switzerland. We present 13.3 nm lines on a 14 nm half pitch, with an LWR of 2.97 nm and dose of 26 mJ/cm² and 14.7 nm lines on a 15 nm half pitch, with an LWR of 2.72 nm and dose of 34 mJ/cm²

Extreme ultraviolet (EUV) lithography is in the phase of first generation of high volume manufacturing. Next generation EUV lithography requires further improvement of resist performance such as resolution, sensitivity and pattern roughness. Therefore, it is important to understand deeply both photon and materials stochastic effects for 5 nm node and beyond. Stochastic effects in EUV resist is much sever than that in ArF resist due to less photon number. In this paper, we investigate EUV resist stochastic effect to find suitable material approaches for further improvement. Many research groups have reported that additives such as PAG and Quencher distribution and aggregation in resist film cause resist stochastic. We have also investigated additive distribution and aggregation behavior in EUV-CAR system using advanced resist analysis method. Film analysis result indicates that both additives distribution and aggregation are not main factors causing resist stochastic degradation. To improve resist stochastic, we have been trying to control chemical reaction during and after exposure. As one of our strategy, new type of PAG with high acid yield to utilize EUV photons effectively has been developed. In addition to PAG, we also developed uniform polymer and high contrast polymer for better resist dissolution during development process. Resist systems with new high acid yield PAG and new polymers show excellent resist and defect performance through resist stochastic improvement.

Metal contaminants are notorious yield detractors throughout semiconductor unit processes. Metallic contaminants can create small, hard-to-detect defects that can eventually result in cone defects and gate leakage. Because these contaminants are so hard to detect, it is extremely difficult to pinpoint their root cause and identify opportunities to remove them. Clean photochemicals experience many contamination opportunities between their final quality control checks at the end of manufacturing and dispense onto a wafer. The complexity of the interactions of metal contaminants and the components in photochemicals is an important consideration when designing removal methods. This challenge increases when metaloxide photoresists are introduced into high volume manufacturing, whereby metals that enhance etch resistance must remain in the formulation, while specific metal contaminants must be removed. In this paper, we will describe different types of metal contaminants in photochemicals and raw materials, review how these contaminants are removed using membrane-based technologies, and define new methodologies to better target metal in photochemicals.

In EUV lithography, spin-on silicon hardmasks have been widely used not only as etch transfer layers, but also as assist layers to enhance the lithographic performance of resist. In this study, we demonstrate a novel approach to functionalize spin-on silicon hardmasks by hybridizing them with functional groups through a sol-gel approach. By varying the concentration and type of the functional groups, the structure and property of the hardmasks can be tuned effectively, especially in the aspects of surface energy, elemental composition, and hardness. The lithographic performance of the functionalized hardmasks was evaluated using NXE3300 EUV exposure system to print line-space features with a targeted CD = 16 nm half pitch. Evidenced by the results, when the functionalized hardmasks were used as underlayers, the resist exhibits large processing window with the printable CD ranging from 11.9 to 19.7 nm and a biased 3-sigma line width roughness = 3.73 nm. In contrast, on a non-functionalized spin-on hardmask, no feature can be printed. Finally, the CF₄ and O₂ plasma etch rates of the hardmasks were tested to evaluate the impact of functionalization on their etch-selectivity.

The combination photoresist-underlayer fulfills a central role in EUVL for patterning. Moreover, future high numerical aperture (NA) and tight pitches will require very thin layers in the lithography stack, which will increase the impact of chemical interactions at the photoresist-underlayer interface. Adhesion between these layers will be critical to overcome pattern collapse at high aspect ratios whereas at the same time the impact of interfacial effects, such as intermixing, on the lithography performance must be minimized. A fine balance must be found between several chemical interactions, which is a complex exercise with many unknown parameters. In this paper we present how the polar and dispersive components of the surface energy can be used to optimize EUV underlayers in order to achieve the best lithography performance. Subtle changes in the underlayer composition can have a large effect on the lithography performance. A PTD CAR photoresists test case will be used to demonstrate that the photoresist profile, scum formation, line width roughness, pattern collapse and stochastic defects can all be tuned into a certain direction just by tweaking the surface energies of the underlayer. The simplicity of the methodology in this study will be a powerful knob to understand and optimize underlayers for EUV photoresist-underlayer interactions.

Silicon hardmask (Si-HM) materials used in lithography processes play a critical role in transferring patterns to desired substrates. In addition, these materials allow for the tuning of optical properties such as reflectivity and optical distribution for better lithography. Si-HM materials also need to possess good compatibility with photoresists before and after optical exposure, during which the photoresist in the exposed area may change polarity. Therefore, Si-HM materials may benefit from adaptive or amphiphilic capabilities to keep both exposed and unexposed photoresist compatible with the substrate. In this work, we will demonstrate that Si-HM surfaces may be adaptive or amphiphilic through both experiments and computer simulation. Specifically, we will demonstrate that the functional groups (polar and nonpolar) at the Si-HM surface may be switchable, and the surface will be dictated by the environment to which the Si-HM is exposed. Knowing the adaptive capability of Si-HM materials will greatly facilitate the development of better underlayer materials for improved lithography.

In the multilayer patterning process, underlayer material is often used to enable device size shrinkage for advanced integrated circuit manufacturing. This underlayer material, spin on carbon (SOC), with high etch resistance plays an important role in both gap fill and process of transferring high aspect ratio patterns. Good global planarization (PL) performance over various pattern topographies not only impacts on the following lithography process window but also boosts the overall device integration yield (Figure 1). As critical dimension (CD) size decreases in the advanced nodes such as 10 nm and beyond with multiple patterning steps, long range planarizing SOC material is needed to control the CD uniformity. During the single coat and single bake process, thermal flow ability of these carbon rich materials is one of the key property to achieve long range planarization performance. In addition, our strategy for designing long distance thermal flow polymers will be applied to both low/high thermal stability SOC materials. Herein, we report the development of a novel planarized SOC materials with good Fab drain line compatibility. As for material global planarization performance, the observation of flow ability can be monitored through the various cure conditions. Other key performance such as gap fill, etch rate toward various gases, solvent strip resistance and cured film thermal stability will be also highlighted in this paper.

Irresistible Materials has previously introduced the HM340 series of fullerene based spin-on carbon hardmasks, and reported on material characterization, including very high carbon content and high thermal stability. The materials have a low Ohnishi number providing high etch durability and the low hydrogen level allows for high resolution etching without wiggling. In order to further increase semiconductor facilities (Fab) compatibility, thermal stability and etch resistance several new formulations are under development. Here we present the latest results for our new HM1360 series, avoiding the drain test issues encountered with higher concentration HM340 formulations, together with new and updated characterisation results for the more advanced formulations.

This study focused on the defect behavior analysis with CD variation on EUV via hole pattern using photolithographic process and etch transfer performance. While defect requirements are not as stringent for memory devices, logic devices must be defect-free. Currently, a defect which comes from the process or material can only be detected by top-down inspection approach, however, it is difficult to detect killer defect types such as incompletely opened holes. To develop 5- nm logic node, a hole pattern 15 nm or smaller is required. Identification of failure at the bottom of the hole becomes more challenging. Nevertheless, the process window margin by the amount of dose/focus is not fully explored to find the defect occurrence tendency. So far, there are reported analyses on the scaling of pattern and pitches. In this paper, we examine the process margin quantified by not only by exposure latitude and depth of focus, but also the comprehensive defect –free process window. In our previous study, the behavior of missing-hole type defects was examined and robust defect suppression result was introduced by utilizing a newly developed etching recipe.^1,2 In this study, we optimized CD variation and defect reduction comprehensively, to introduce successful improvement results of a wide defect process window with a narrow CD distribution.

To meet the International Roadmap for Device and Systems (IRDS), the development of an advanced lithography process for next-generation (NG) technology node is a vital and challenging task, as we are reaching to its physical limits. In the progress of high volume manufacturing (HVM) at sub-12 nm node, it is very important that resist materials should possess low line edge roughness (LER) and high sensitivity (E0) using extreme ultraviolet (EUV) and its analogous exposure systems. Apart from standard chemically amplified resist (CAR), acid-free non-CAR has been studied immensely as a potential candidate for NG patterning. To achieve sub-12 nm patterns, a complete study for newly developed n-CAR is required to make sure that developed resist formulation is performing optimally. Aside from the n-CARs, we adopted a novel patterning approach using He⁺ ion beam lithography with less proximity effect. Here we present the metallic nanoparticle photo-multiplier (high optical density materials for λ ~13.5 nm) embedded with n-CAR for better photo-absorption and high-resolution pattern development. The silver (Ag- OD 12 w.r.t Carbon) nanoparticles (NPs) with ~2 nm regime were embedded into MAPDST homo-polymer ((4-(methacryloyloxy)phenyl) dimethylsulfonium trifluoromethanesulfonate). To investigate the high-resolution patterning synthesized photoresist was exposed to e-beam (E_e) and Helium ion (E_He) beam lithography. The patterned samples were developed in aqueous solution and revealed the negative tone with the sensitivity of 172 μC/cm² and 50.4 μC/cm² for E_e and E_He respectively. The MAPDST-Ag resist found stable for more than 1 year, which clearly suggests that there is no sign of Ag-NPs agglomeration in the formulation. Thence, evidently, prove the considerable shelf life of developed resist formulation and can be used in NG semiconductor device HVM and other electronic device applications.

In this manuscript, various fluorine-containing BCPs were synthesized by living anionic polymerization or reversible addition−fragmentation chain-transfer (RAFT) polymerization. The resulted BCPs showed high χ value > 0.2. With similar χ value, we observed that PS-typed BCPs formed microdomains of 5 nm within 1 min at 80°C, whereas polymethacrylate-typed ones required 1 h annealing at 160°C. When rigid side chain was incorporated into the polymethacrylate block, the annealing time can be shortened to 5 min at 160°C. However, the poor film formation of the such BCP with rod-like side chain resulted in rough line pattern after the thermal annealing process. The polymethacrylate-typed BCPs generally requires high boiling point solvents for better film formation and better line patterning.

This paper introduces line roughness characterization non-straight patterns made of block copolymers (fingerprint patterns). Line Width Roughness have been determined using Power Spectral Density based on a special edge detection developed at CEA-LETI to extract edges contours. We investigated several process parameters impact on LWR such as the degree of polymerization of different BCPs and the impact of UV irradiation on the roughness of the PS block.

Directed Self Assembly (DSA) is a promising technology for complementary patterning in future nodes. As DSA patterning has continued to evolve there has been many efforts to improve defect performance using hardware, processes, and materials. Traditionally, in PS-b-PMMA block-copolymers (BCP) based patterning schemes, phase separation is achieved using a thermal annealing with controlled temperature and time. In previous work we have expanded our understanding of BCP annealing by demonstrating the ability to improve a process window and fingerprint formation of a lamellar system (31nm pitch BCP) by atmospheric condition control during the thermal anneal, as shown in Figure 1. By reducing the oxygen concentration inside the annealing chamber, we have demonstrated improved densities for fingerprint defects commonly associated with phase separation in BCP systems. Furthermore, by achieving a strong regulation of the concentration at different levels, we have achieved a better understanding of what might be required to fully eliminate these defects for subsequent studies and learning toward device manufacture. By reducing the concentration of oxygen during the thermal anneal process, we have been able to employ noticeably higher annealing temperatures without damaging the BCP films. Ultimately, our goal is to provide an annealing solution that is amenable to high volume manufacturing. In this study, controlled oxygen annealing of a 31nm pitch BCP is evaluated against a known thermal annealing baseline. Oxygen concentration, temperature and time are finely tuned in the study. Finally, polymers with different compositions (ie morphologies: lamellar, PS cylinders, PMMA cylinders) are evaluated, and the correlation between thermal budget and polymer stability is reported.

Block copolymers (BCPs) are appealing materials to the lithography community because of their potential to extend Moore's Law beyond the 10nm node. Not only do BCPs have the ability to microphase separate into structures such as cylinders and lamellae at single-nm length scales, but device fabricators also have control over the alignment of these structures by manipulating the energy landscape of the substrate via directed self- assembly (DSA). Despite the promise that BCPs show in offering an economical enhancement to optical lithography, the levels of defectivity in BCP-patterned devices are still above the desired levels for industrial- scale implementation. A troublesome defect mode that has been observed in experimental BCP structures is the bridge defect. Previous simulation studies by Henderson and coworkers have shown that affinity defects in chemoepitaxial underlayers have the potential to spawn bridge defects in the overlying BCP film. An important consideration in characterizing bridge defectivity is to evaluate and determine which BCP material properties are capable of inhibiting bridge propagation through a BCP film aligned atop an underlayer containing an affinity defect. In this work, coarse-grained molecular dynamics simulations were used to model BCPs with various energetic and structural properties to identify which properties impact bridge propagation. Although there was minimal correlation between BCP properties and bridge propagation, a kinetic survey showed that bridge defects generally reached their maximum thickness within the first 100ns of thermal annealing. As the BCP began undergoing long-range alignment, the bridges slowly healed before reaching an equilibrium thickness of roughly one BCP chain.

We develop maleimide derivatives named “NeoFARIT N0XX (NFN0XX)” series which show excellent thermal stability as SOC materials. [1] For example, NFN006 shows a slight weight loss <1% at 400ºC in the air atmosphere on TG-DTA analysis, and <5% of weight loss at 450ºC. However, NFN006 has a problem of high shrinkage during baking process. Sublimates are observed at the thin film forming process with 250ºC baking condition, and lead to shrinkage and defects on coating and baking process.

In this paper, we report further improved thermal performance of maleimide resin called NeoFARIT N011 (in short NFN011) with lower shrinkage during curing process. The shrinkage of NFN011 in 250ºC bake is less <5% in the air although that of NFN006 reaches more than 20%. In addition, NFN011 with no additive is able to form a cured film with low shrinkage due to low sublimation, and shows better thermal stability than cured films using additives.

On the other hand, NFN011, which exhibits excellent thermal stability, has a problem of low solubility in PGMEA and PGME, which are commonly used solvent in lithography processes. On this solubility issue, we newly develop NeoFARIT N012 (in short NFN012), which includes a methyl group on the maleimide moiety of NFN011. NFN012 shows both good solubility in PGMEA and sufficient thermal stability. It shows slight weight loss <5% at 450ºC in the air atmosphere on TG-DTA analysis. In addition, its shrinkage in 250ºC bake is less <5% in the air. We have succeeded in developing a new material that exhibited good solubility in PGMEA and PGME, sufficient thermal stability, and low sublimability.

As the critical dimension (CD) in semiconductor devices continues to shrink, the multilayer patterning process to transfer fine line patterns into an underlying substrate is becoming increasingly important. The trilayer processes consist of a photoresist film, a silicon-containing layer and a carbon rich underlayer. The distinctive difference in etch selectivity toward fluorine and oxygen based reactive ion etching (RIE) chemistry is critical to provide highly selective pattern transfer to the substrate. In response to the need for high etch resistant underlayers, we have developed carbon rich spin-on carbon (SOC) materials with good solubility in preferred casting solvents, high thermal stability and high dry etch resistance. To better understand structure-property relationships of high etch resistant SOC films, cured SOC films were analyzed by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The design considerations for high etch resistance SOC underlayers, such as Ohnishi parameter, crosslinking and film density, will be discussed in this paper.

Multilayer lithography is used for advanced semiconductor processes to pattern complex structures. As more and more procedures incorporate a high-temperature process, such as chemical vapor deposition (CVD), the need for thermally stable materials increases. For certain applications, a spin-on carbon (SOC) layer under the CVD layer is required to survive through a high-temperature process. Additionally, these materials are sometimes desired to planarize the underlying topography. Designing organic films that have high-temperature stability while also allowing for good planarization is a challenge. Rigid polymers are typically very stable, but planarizing materials are normally highly flexible, so the trade-off between properties has to be carefully designed. The materials presented in this paper are stable up to 500°C, soluble in the solvents commonly used in the semiconductor industry, provide void-free fill in high-aspect trenches, and have excellent planarization properties. The coated film has very low shrinkage through the bake temperature and is stable at high-temperature conditions. The planarization on topography in the range from local distance (a few microns), to global distance (a few hundred microns) is equivalent to our best low-temperature SOC.

As device design scales and becomes more complex, fine control of patterning and transfer steps is integral. Planarization of deep trenches and via arrays has always been a challenge. Aspect ratios continue to increase while critical dimensions shrink, and typical trench fill schemes are no longer able to meet the fill and planarization requirements. Traditional design of spin-on carbon (SOC) materials for planarization normally incorporates low viscosity and high crosslink temperature to allow for the material to thermally flow. However, thermal flow is limited by the force needed to drive this flow, the crosslinking reaction, and the surface tension. This is especially important in deep trenches and vias, where there is a need to move a large amount material. A new type of planarizing material is presented that uses Marangoni effect to pull material to the dense feature area. This force is much stronger than gravity during thermal reflow, and it can be controlled by careful selection of material and process. Based on the structure of substrate, it is possible to adjust the intensity of force and balance with viscosity and flow time to achieve perfect planarization. The technology is not wavelength-specific and could be used in lithography applications from i-line to EUV. The design can also be incorporated into a wide range of SOC platforms for both low- and high-temperature applications.

The silicon hardmask (Si-HM) is one of the key materials used in multilayer lithography for pattern transfer to a substrate using a fluorinated plasma etching process. Manufacturing of devices with smaller feature sizes introduces new challenges in defect control of all the critical layers, including the Si-HM layer used in photolithography. One of the major challenges of Si-HM materials includes intrinsic defect formations, which can be exacerbated by the presence of foreign contaminants such as soft and hard particles, organics, and metal-ionic contaminants. These contaminants are also known to induce defects by interfering with the plasma etch processes used in advanced patterning technologies. The contaminants can range from microns to angstroms in size. The identification and characterization of the defect adders is important to develop filtration methods capable of minimizing the number of on-wafer defects and consequently improving the quality. In this study, metal contaminants, liquid particle count and on-wafer defects of Si- HMs and filtration removal rates are monitored to determine the effect of filter type, pore size, media morphology, and cleanliness on filtration performance. 5-nm PTFE NTD2 filter having proprietary surface treatment used in this study shows lowest defect count.

The purification method to produce highly pure products containing siloxane polymer was developed. Siloxane polymer can be difficult to be purified without changing its property because of its high reactivity. Of various methods, ion exchange is well known as a useful method for a purification. However, resins with cation or anion exchange groups used in the purification process can promote hydrolysis and dehydration condensation reaction of siloxane polymer. That is why the method had not been used for the purification of siloxane polymer. In this study, conditions of the ion exchange method were reviewed. As a result, it was found that using strongly acidic cation exchange resins with gel structure is a proper condition. And also simulation models of the polymerization of siloxane polymer and the ion exchange reaction were applied to the purification process. By using these simulations, process parameters of the purification such as process time for ion exchange can be optimized.

Our earlier studies pointed to a strong correlation between the molecular weight of novolac resin and lithographic characteristics. In particular, they showed that the resolution and DOF characteristics of resists may be improved by controlling molecular weight distribution. The present study focuses on photoactive compound (PAC) structure and resin structure. This paper discusses the effects of differences in PAC ballast structure and the composition of m-cresol (metacresol), p-cresol (para-cresol), and xylenol, phenolic monomers that constitute novolac resin, on resolution and lithographic characteristics, based on development rates and resist pattern simulations.

The dissolution behavior of a photoresist film is analyzed by a confocal laser scanning microscope (CLSM) in this work. Results show that the existence of a local condensation of a TMAH developer at the interface of the photoresist/glass substrate interface at the initial stage of the photoresist dissolution. The uniformity of the local condensation of the TMAH developer depends on the amount of a remaining solvent in the photoresist film. Moreover, results indicate that the uniform/ununiform penetration path results in the uniform/ununiform local condensation of the TMAH developer. Importantly, the ununiform penetration path and local condensation cause the excessive contacting duration at the edge of an unexposed region of the photoresist which causes to form the photoresist pattern edge roughness. The uniformity of the penetration path of the TMAH developer is critical for the photoresist pattern edge roughness.

In lithography, peeling and collapse of photoresist patterns cause difficulties of micro fabrication. In order to prevent the destructions, enhancement of adhesion between the photoresist and substrate is effective. Therefore, significance of accurate adhesion analysis increases with miniaturization of device process. The destructions of photoresist/substrate interface can be mainly categorized into interfacial and cohesive failures. In this study, we propose the direct analysis of adhesion in nanoscale area. Using AFM, we estimate adhesion energy of AFM-tip/Si interface in local area and identify the destruction mode of photoresist/Si interface. First, we evaluates the adhesion between photoresist films and surface modified Si substrates. From the surface free energy analysis, the threshold adhesion work, 𝑊_𝐴𝑡ℎ (J/m²) of photoresist/Si interface is estimated to be 71.7 mJ/m² in order to identify the destruction mode in macro area. Secondary, the interaction between the AFM tip and the surface modified Si substrates are evaluated in the local area less than 10 nm in diameter. The interaction energy, 𝐸_𝐼 (J) of AFM-tip/Si interface shows a positive correlation with the adhesion work of photoresist/Si interface. We estimate effective area for adhesion of AFM-tip/Si and adhesion energy, 𝐸_𝐴 (J/m²) of AFM-tip/Si in nanoscale area. The results predict that only interfacial destruction occurs at photoresist/Si interface when the adhesion energy of AFM-tip/Si is less than 44.7 mJ/m². We can expect that the quantitative analysis of nanoscale adhesion contribute to improve the accuracy of nanolithography process.

Some hybrid inorganic-organic resist materials known as metal-oxo clusters were synthesized and lithographic characteristics were investigated. In particular, the dissolution behaviors of metal oxo clusters were investigated by development analyzer. Our results indicated that the solubility of metal oxo clusters thin films decreased by the exposure to KrF, ArF and electron beam (EB). We clarified the sensitivity in Ti-based oxo clusters was higher than that of Zr-based oxo clusters in both KrF and ArF exposure. The dissolution rate in two kinds of metal oxo cluters was almost same in both KrF and ArF exposure. Furthermore, the dissolution contrast of Ti-based oxo clusters was higher compared to Zr-based oxo clusters. Metal oxo clusters resists have the potential as future negative tone photoresist and EB resist materials.

The progression of EUV (Extreme Ultra-Violet) lithography into high volume manufacturing is driving the evolution of increased photochemical purity requirements. Further scaling will intensify the challenge to improve inline yield, ensure supply chain integrity, and increase reliability. Si hardmask materials play an important role in pattern transfer, and therefore require strict compositional materials integrity and stability to ensure expected performance. It is therefore critical to assess interactions between Si hardmask materials and components in the chemical delivery system to ensure hardmask materials purity and overall integrity.

There has been an increasing demand on filtration technology to enhance material purity in semiconductor unit processes. Many efforts to improve filtration have focused on establishing retention ratings using various particulate contaminants. While this is an important parameter to understand particle removal, it is equally important to understand the fundamental interactions between photochemicals and filters. As materials change and the smallest defects become even more challenging to detect, new filter screening methodologies are needed to address the most stringent defect targets.

In this paper, a novel filter screening metrology is introduced to identify optimized filtration candidates for specific defect sources and improve defectivity in Si hardmask materials. Results and possible mechanisms of defect reduction will be discussed.

Extreme ultraviolet (EUV) lithography has gained momentum towards high-volume manufacturing (HVM) as the method of choice for sub-20 nm half-pitch device fabrication. Optimized EUV photoresists and an improved understanding of the EUV patterning mechanisms have made significant progress toward achieving improved resolution, line-width roughness (LWR), and sensitivity. In addition, introducing a thin EUV underlayer (UL) into the regular EUV materials stack enhances the overall performance of EUV resists and opens the process window. As with all other spin-on photochemicals, utilizing filtration at the point-of-dispense can effectively reduce coating defects of the EUV underlayer material.

In this paper, we will describe our efforts to leverage different filtration parameters, including retention ratings and membrane materials, to understand their impact on EUV underlayer coating defects, and will present the characterization of coating defects in very thin films.

NTD (Negative Tone Developer) technology with application of developer to ArF immersion is one of the technologies that is well known and widely used for enabling better optical image contrast. For critical layer processes, CD (Critical Dimension) control is more difficult with narrow trench and contact hole pattern. Since it is difficult to obtain better CDU (Critical Dimension Uniformity) once mask and resist set have been fixed, new NTD processes are required to improve it. CXMT (Chang Xin Memory Technologies) has been continuously developing manufacturing processes based on new NTD method for narrow pattern DRAM process with TEL™ (Tokyo Electron Limited). In this paper, we discuss our work for CDU improvement with new process on Global, Inter, and Intra shot CDU as well as the optimization results of chemical consumption.

One of the main challenges of a Dual Damascene (DD) via-first process is the control of the Critical Dimensions (CDs) in the lithography of the trenches. The PhotoResist (PhR) thickness presents variations from the via arrays to the open areas, which cause the variation of CDs: the swing effect.
The planarization of a DD via-first process is reported. A dual-layer solution is used to demonstrate the complete filling of deeply etched structures and the advanced planarization in a multilayer technique. The first material coating the substrate exhibits a Marangoni effect; the second material owns the same physico-chemical properties of the first one, except for the Marangoni properties.
The Marangoni effect of the first coating produces a thicker film in the via array than in the open area, resulting in a negative Film Thickness (FT) bias. Then, the coating with second material is performed and having it standard planarization properties, a positive thickness bias occurs. The addition of these two coatings results in a thickness bias intra-die and on complex topographies, ranging from 0 nm to 30 nm across the wafer. Additionally, the similar physicochemical nature of these two planarization materials enables this dual layer system to be treated as a single homogeneous layer as far as the etching process is concerned.
In the perspective of a KrF lithographic process, this dual-layer offers a planar substrate to be coated with the PhR and allows a strong reduction of the intra-die swing effect, providing a scalable solution.